Rifled slug

ABSTRACT

The invention relates to a rifled slug provided with a metal head ( 1 ) and a plastic rear part ( 2 ), which is made as a single piece from a pin-shaped front part ( 5 ), with a rod-shaped middle part ( 6 ) joined to the rear of said front part, and with a plunger-shaped rear part ( 7 ). The front part ( 5 ) is inserted from the rear into a pocket hole of the metal head ( 1 ) and is joined thereto in a captive manner. The aim of the invention is to improve a rifled slug of the aforementioned type whereby increasing the precision, i.e reducing the dispersion in the target. To this end, the front part ( 5 ) is provided in the form of a hollow body and is joined to the middle part ( 6 ) via a predetermined breaking point ( 14 ), whereby when shooting, the middle part ( 6 ) slides into the cavity of the front part ( 5 ) until the upper surface ( 19 ) of the rear part ( 7 ) strikes the lower surface ( 20 ) of the front part ( 5 ).

The invention relates to a gun-barrel projectile having thecharacteristics of the preamble of claim 1.

This type of gun-barrel projectile is described in EP 0 341 543 B1. Theupper part of the end part of this projectile is formed as a solid body.It has a slight radial expansion vis-à-vis the blind hole of in the leadhead, so that it has to be inserted into it using a force. Then, at aplurality of locations on the periphery of the lead head, preferably atthree places distributed uniformly on the periphery of the lead head,lead is driven pointwise radially inwardly, where the displaced leadflows into a peripheral groove of the upper part of the end part. Thisinward displacement of lead occurs using rod-shaped steel pins similarto a punched-in part. In virtue of the force fit of the upper part ofthe end part in the lead head and the pointwise incorporation of thelead in the upper part of the end part, the latter can be joinedcaptively with the lead head.

In the case of this prior art gun-barrel projectile a predeterminedbreaking point is arranged between the rod-like central part and thepiston-like bottom part of the end part, said breaking point beingobtained at the time of manufacture in an injection molding process byinsertion of a metal sleeve into the mold. This manufacturing process isrelatively costly and prolongs the cycle time at the time ofmanufacture. A further drawback is the fact that the predeterminedbreaking point cannot be configured very uniformly. This has negativeeffects on the internal and external ballistics of the projectile.

In the evolution of firing the piston-like end part shifts upwards onthe rod-like central part after detachment of the predetermined breakingpoint, until its upper side contacts the underside of the upper part. Abarblike projection encircling the rod-like central part holds the endpart on the central part thus preventing the central part from detachingitself rearwardly from the rod-like central during the flight phase ofthe projectile. During the flight phase the rear end of the rod-likecentral part projects rearwardly from the piston-like end part. This isa drawback for the external ballistics of the projectile, because of theflow conditions resulting therefrom in the posterior zone of the rearpart. Also disadvantageous in this respect is the fact that therearwardly projecting end of the rod-shaped central part is non-uniformin its external form because of the manufacturing process described.

In the hereinbefore described gun-barrel projectile a very good dampingof the gas pressure increase is noted in the barrel. Nevertheless thepredetermined breaking point rends after firing because of therelatively large tolerances from cartridge to cartridge caused by themanufacturing process at relatively widely differing gas pressures. Thishas effects on the further pressure development in the barrel andconsequently on the exit velocity of the projectile. Accordingly, itleaves the barrel from firing to firing with relatively widely varyingvelocity, whereby target precision suffers.

The object of the present invention is to improve upon genericgun-barrel projectile, in that precision is increased; that is, thetarget spread is reduced.

This object is achieved according to the invention by the gun-barrelprojectile having the characteristics of claim 1.

In the rear part of the gun-barrel projectile according to theinvention, therefore, there is the predetermined breaking point betweenthe hollow upper part and the rod-shaped central part. It can bemanufactured at this position substantially more precisely and morecost-effectively than at the position according to the prior art anddiscussed hereinbefore. A rending results upon lower gas pressurevariations due to the lower tolerances of the predetermined breakingpoint; in other words, the gas pressure range in which the predeterminedbreaking point rends is smaller than in the prior art gun-barrelprojectile. This has direct positive ramifications on the targetaccuracy.

A further advantage of the gun-barrel projectile according to theinvention is in the fact that the posterior end of the rear part isformed in the flight phase by the formally precisely definedpiston-shaped rear part. This results in defined flow relations, whichpositively influence the external ballistics of the projectile.

Other advantageous embodiments of the gun-barrel projectile aredisclosed in the subordinate clams. The invention will be explained morecompletely in the following using an exemplary embodiment. In therelevant drawings:

FIG. 1 represents a side view of a gun-barrel projectile before firing;

FIG. 2 represents an illustration of the gun-barrel projectile accordingto FIG. 1 after firing;

FIG. 3 represents a perspective representation of the rear part of thegun-barrel projectile before firing;

FIG. 4 represents a side view of the rear part corresponding to FIG. 3;

FIG. 5 represents a section A-A according to FIG. 4, and

FIG. 6 represents an illustration of FIG. 5 after firing.

FIG. 1 represents a gun-barrel projectile, which is loaded in this formor in this condition by the manufacturer. It comprises a heavy lead head(1) and a lighter rear part (2) made out of lighter plastic. Because ofthe mass distribution, the gun-barrel projectile after leaving the gunbarrel stabilizes in flight according to the arrow principle, becausethe center of gravity lies in front of the air attack point.

The lead head 1 has an essentially cylindrical shape and on its frontsurface it has a tip 3, which is intended for improving the airresistance. Slanted guide ribs 4 are distributed uniformly on theperiphery. These guide ribs 4 enable passage through the choke of a gun,because they are urged away because of the ductility of the alloyed leadupon passing the choke. The load of the choke is, therefore, is nogreater than in lead shot upon firing from the gun-barrel projectile.

The rear part 2, whose embodiment is best seen in FIG. 3-5, is made ofplastic in one piece using an injection molding technique. It consistsof a anterior part 5, a central part 6 and a posterior part 7. Theanterior part 5 has a hollow cylindrical body 8, which continues into aflange 9 of greater diameter towards the central part 6. In theassembled gun-barrel projectile (FIG. 1) the hollow cylindrical body 8is seated with a slightly greater dimension in a correspondingcylindrical chamber in the lead head 1, which is not apparent from thediagrammatic representation. Along with the force fit between thischamber in the lead head 1 and the hollow cylindrical body 8 the captiveconnection of the lead head 1 and the rear part 2 is obtained, in thatthe lead is pressed by means of a needle-like stamp in the fashion of apunched-in part into a peripheral groove 10 of the hollow cylindricalbody 8. This type of punched-in part 11 can be seen in the diagrammaticrepresentation according to FIGS. 1 and 2. In general, the connection ismade by means of two or three punched-in parts 11 evenly distributed onthe periphery.

The flange 9 of the anterior part 5 serves as the support for the rearsurface of the lead head 1. In this fashion, upon firing, inco-operation with the hollow cylindrical body 8 an even distribution ofthe gas pressure is produced on the lead head 1.

The anterior part 5 is provided with four air channels 12, which arearranged evenly on the periphery. When the lead head 1 is in place,these air channels 12 create a communication between the inside space ofthe hollow cylindrical body 8 and the atmosphere. They extend throughthe anterior face of the hollow cylindrical body 8, which abut in theassembled condition on the bottom of the chamber in the lead head 1, andthen run one the outside of the hollow cylindrical body 8 over theflange 9 outwards. In addition, in the interior walls of the hollowcylindrical body 8 a flange 13 is provided by means of a increase indiameter. The function of the air channels 12 and of the flange 13 isexplained in more detail in the following.

The central part 6 connects with the anterior part 5 via an annularpredetermined breaking point 14. It is cylindrical and executed as ahollow body. The predetermined breaking point 14 can be produced at thispoint using an injection molding method relatively easily and withlittle variation in tolerance. On the outside surface, peripherallydistributed barbed segments 15 are formed at the transition between thecentral part 6 and the anterior part 5, which—as will be explained inthe following—co-operate with the flange 13 of the anterior part.

The central part 6 transitions—as can be seen particularly in FIGS. 5and 6—relatively thickly walled into the posterior part 7, so that atthis transition point no break or no deformation can from at the time offiring. The posterior part 7 is configured as an rearwardly open hollowcylinder, if a central plug 16 is eliminated. The posterior part 7 hasthe approximate diameter of the flange 9 of the anterior part 5 andterminates at the posterior end with a peripheral seal lip 17, whichserves at the time of firing to seal the gas pressure to the barrel. Forstabilizing the walls of the posterior part 7, same is provided withreinforcing ribs 18 distributed over its periphery.

In the following, the co-operation of the lead head 1 and the rear part2 at the time of firing is described.

As has already been explained hereinbefore, FIG. 1 represents the loadedcondition of the gun-barrel projectile. After firing of the propellantcharge, a gas pressure builds, which acts on the cross-sectional area ofthe posterior part 7. Due to this pressure build-up, the predeterminedbreaking point 14 rends and the central part 6 pushes—because of theinertia of the heavy lead head 1—into the interior of the hollowcylindrical body 8 of the anterior part 5. That happens abruptly. Whenthis happens, the air forced out of the inside space of the hollowcylindrical body 8 can flow off easily via the air channels 12, so thatthe incursion of the central part 6 into the anterior part 5 does notencounter any resistance due to pressure accumulation. At the end ofthis movement of the now two-part rear part 2, the upper surface 19 ofthe posterior part 7 contacts the lower surface 20 of the anterior part5. The gun-barrel projectile has thus assumed the form represented inFIG. 2, with which it leaves the barrel of the weapon. This form ismaintained until striking the target, because the central part 6 and theposterior part 7 are captively connected to the anterior part 5. Thisconnection is realized by the co-operation of the barbed sections 15 ofthe central part 6 and the flange 13 in the inside walls of the hollowcylindrical body 8. After maximum depth penetration of the central part6 into the anterior part 5, the barb-shaped sections 15 lock behind theflange 13, so that the central part 6 can not separate, at least not bythe forces acting on the rear part 2 during the flight of the gun-barrelprojectile. The engagement between the anterior part and the centralpart 6 and posterior part 7 is sown in FIG. 6.

1. A gun-barrel projectile having a metal head and a rear part made ofplastic, which is manufactured in one piece from a pin-shaped anteriorpart, a rod-shaped central part connecting rearwardly therewith and apiston-like posterior part, wherein the anterior part inserts rearwardlyinto a blind hole of the metal head and is captively connectedtherewith, characterized in that the anterior part (5) is executed as ahollow body and is connected with the central part (6) via apredetermined breaking point 14), whereby at the time of firing thecentral part (6) pushes into the hollow space of the anterior part (5)to such an extent, that the upper surface (19) of the posterior part (7)contacts the lower surface (20) of the anterior part.
 2. The gun-barrelprojectile according to claim 1, wherein the anterior part (5) isprovided with air channels (12), which make possible flow of the airforced into the hollow space of the anterior part (5) upon penetrationof the central part (6).
 3. The gun-barrel projectile according to claim1, wherein barb-shaped sections (15) are provided on the central part(6), which upon penetration of the central part (6) into the hollowspace of the anterior body (5) grab behind a flange (13) in the watts ofthe hollow space of the anterior part (5).
 4. The gun-barrel projectileaccording to claim 2, wherein barb-shaped sections (15) are provided onthe central part (6), which upon penetration of the central part (6)into the hollow space of the anterior body (5) grab behind a flange (13)in the walls of the hollow space of the anterior part (5).